Internal combustion engine radio frequency radiation suppressing ignition system



United States Patent 72] Inventors Charles L. Dusenberry,

Chesterfield, Ind.; Richard E.

Massall, Flint, Mich.; John R. Snead,

Kokomo, Ind.; Richard J. Hanson,

Warren, Ohio, Paul W. Wood, Warren,

Mich.; Jack E. Riley, Alexander, Ind.,

and James V. Clore, Howell, Mich.

Feb. 17, 1969 Continuation-impart of Ser. No. 761,193,

Sept. 20, 1968, abandoned.

Nov. 24, 1970 General Motors Corporation Detroit, Michigan a corporation of Delaware [54] INTERNAL COMBUSTION ENGINE RADIO FREQUENCY RADIATION SUPPRESSING IGNITION SYSTEM 5 Claims, 2 Drawing Figs.

[21] Appl. No. [22] Filed [45] Patented [73] Assignee [52] U.S.Cl I23/l46.5, l23/l48z200/l9 [51] Int. Cl F02p 7/02 [50] Field ofSearch 123/143A,

148R11 1 46:5A;g1 Ii/146,149; 74/120, 152; 200/19, 25; 315/58 [56] References Cited UNITED STATES PATENTS 2,684,451 7/1954 Castongay 313/146 2,714,623 8/1955 Wolcott 174/120 3,244,924 4/1966 Berg et a1..... 313/149X 3,235,655 2/1966 Counts et al. 174/152 3,348,013 10/1967 Waggoner 200/19 Primary Examiner-Laurence M. Goodridge Attorneys-W. E. Finken and Richard G. Stahr ABSTRACT: An internal combustion engine radio frequency radiation suppressing ignition system which combines a gap of a width which is greater than is currently normal between the rotating terminal and each stationary terminal of an internal combustion engine distributor with television-radio radiation suppression ignition cable and resistor type spark plugs.

Patented Nov. 24, 1970 TO DISTRIBUTOR A In INVENTORS C/ar/a L'. film/Mary,

(Z-Mari 5. Wamdi fad/. .4. zlmai /?21. W Wood, Jack 6. Bile/'34. BYJZZIIMS HC/are ATTORNEY Several arrangements and methods have beendeveloped heretofore in an effo'rtto decrease thisradiated energy, however, most have been found to be unsatisfactory. Although the magnitude of this radiated energy is considerably reduced by.

the use of resistor type spark plugs and television radio suppression ignition cable, a greater suppression of this radiation is desirable. i

lt'ha's been found that a considerably greater reduction of radiated radio frequency energy, 20 to 50 decibels has been measured in the range of l to l,000 megacycles, is realized by providing a distributor having the air gap between the rotating terminal and each stationary terminal of a width whichis greater than is currentlynormal. This phenomena is observable initially at the higher frequencies, in the order of 1,000 megacycles', and, as the gap is increased, a greater suppression is realized toward the lower end of the frequency spectrum. 1

It is, therefore, an object of this invention to provide an improved nternal combustion engine radio frequency radiation suppressingignition system.

It is another object of this invention to provide animproved internal combustion engine radio frequency radiation suppressing ignition system wherein a wide distributor gap is employed in combination with resistor type spark plugs and television-radio'suppression ignitioncable.

In accordance with this invention, an improved internal combustion engine radio frequency radiation suppressing ignition system is provided wherein a wider than normaldistributor gap is employed in combination with resistor type spark plugs and television-radio suppression ignition cable.

For a better understanding of the present invention together with additionalobjects, advantages and features thereof,

- reference 'is made to the following description and accompanying drawingfin which:

FIG. 1 schematically sets forth the vention; and

FIG. 2 is a bottom view of the distributor cap ofFIG. l.

The internal combustion engine radio frequency radiation suppressing ignition system of this invention comprises a re-. sistor type spark plugfor each cylinder of the-internal comignition system of this in- 11 provided with screw threads at its lower end, for threaded connection with the engine, a ground electrode 12 secured to its lower edge and a stepped centerbore 13 forming an internal ledge 14 therein. Positioned upon ledge 14 is an insulator sleeve 15 of a ceramic material which is secured in gas tight relationship with ledge 14. The insulator sleeve 15 is provided with a stepped centerbore 16 to receive and position a center electrode. Positioned in the centerbore overlaying the center electrode 17 IS the resistor-section l8which is in electrical contact withelectrode 17. An upper conductive seal I9 and a lower conductive seal 20 provide a gas tight seal relationship within insulator l5.An upper center electrode 21, in electrical contact with upper seal 19, provides for an electrical connection to an ignition cable. Spark plugs of this type are currently commercially available, described in.U.S.=Pat. No. 3,235,655 which issued Feb! I5, 1966 and is assigned to the assignee of the present invention.

A conventional ignition distributor 25, shown partially in cross section and partially in cutaway, includes a bowl portion 26, a rotor member 27,"a shaft 28, which is gear connected to bustion engine with whieh the ignition system is, to be used, an

ignition distributor having a stationary terminal corresponding plug and a movable terminal rotated in timed I to each spark relation with the engine and positioned to successively pass closely adjacent to each of the stationary terminals, a television-radio suppression ignition cableextending between each. stationary terminal and the corresponding spark plug and an air gap between the ignition distributor movable terminal and each stationary terminal of a width within the range .060 inch to .250 inch at the point of nearest approach.

A resistor'type spark plug of a resistance valve compatible with the associated engine, for example of a valuewithin a range of 1,500 to 50,000 ohms,is provided for each cylinder of the internal combustion system is to be used. In FIG. I of the drawing, which setsforth the ignition system oflthis invention fora 6 cylinder Internal engine with which the ignition,

combustion engine, one resistor type spark plug 10 is shown partially in cross section while the remainder of the spark plugs are schematically illustrated and referenced 10a, 10b, l0c,.I.0d and 10g. The resistor type'spark plug' includes a shell the cam shaft of the associated internal combustion engine, and a distributor cap 29.-A movable terminal 30 is secured to rotor.27, and, consequently, is rotated in timed relationship with the engine therewith. A stationary terminal corresponding to each spark plug of the engine, referenced by numerals 31a, 31b, 31c, 31d, 312 and 31f, in FIG. 2, is provided. Movable terminal 30iof the distributor is positioned to successively pass closely adjacent to each of the stationary terminals, the distance between the end of the movable terminal and each stationary terminal at the point of nearest approach being an air gap 32 which will hereinafter be referred to as the distributor gap.

Extending between each stationary terminal of distributor 25 and the corresponding resistor type spark plug is a television-radiosuppression ignition cable hereinafter referred to as TVRS" ignition cable. Ignition cable of this type is commercially available in a rangeof resistance values between 2,000 and 10,000 ohms per. foot and is comprised of a plurality of straight parallel threads 35covered by a sheath of braided threads 36 .which are impregnated with a suitable car-- bonaceous material such as graphite and enclosed by'a first insulating sheath 37 and a second insulating sheath 38. Although only thecable connected between stationary terminal 31a and the distributor and resistor spark plug 10 is shown in detail in the drawing,

other stationary terminal and the corresponding spark plug is of the same TVRS type. Ignition cable of this type is disclosed anddescribed in US. Pat. No. 2,714,623 which issued tial magnitude induced in the secondary winding of the ignition coil, of course, determines the maximum width of distributor gap 32 as this energy must cross this gap to provide ignition potential across center electrode 17 and ground elec-- trode 12 of each spark plug. Distributor gaps within'a rangeof .060 inch to .250 inch in combination with TVRS" ignitionplugs have provided a radio,

cable and resistor. type spark frequency radiation'suppression" of substantially percent.

In atypical specific, application of present invention, the distributor 25 ternal combustion engine with the TVRS" ignition leads exone specific type being disclosed and it is to be specifically understood that the ignitioncables extending between each the movable terminal '30 of the ignispring contact 42, in

width greater than is currently normal in automotive type engines. Thei'gnition poten the combination .of the was mounted upon the inlending varying distances up to approximately 24 inches from the 513N003!) contacts thereof to the respective spark plugs. Each of the -lVRS" ignition leads had a resistance value of approximately 4,000 ohms per foot and each resistor type spark plug had a resistance value of approximately 5,000 ohms With conventional ignition systems of this type, the distributor gap 32 would be of the order of .032 inch. To provide the combination of this invention, the width of distributor gap 32 mav be progressively increased to a value at which measurements indicate no substantial further reduction of radiated interference. usually of the order of 0.090 inch.

The precise reason an increased length of distributor gap 32 reduces the radiated interference is not definitely known It is believed, however, that increasing the width of thedistributor gap provides a transistory resistance value which approaches the critical damping value of the interference generated upon distributor gap breakdown.

While a preferred embodiment of the present invention has been disclosed and described. various modifications and substitutions may be made without departing from the spirit of the invention. i

We claim' 1. An internal combustion engine radio frequency radiation suppressing ignition system comprising in combination. a re sistor type spark plug for each cylinder of the internal combustion engine with which the ignition system is to be used, an ignition distributor having a stationary terminal corresponding to each said resistor type spark plug and a movable terminal rotated in timed relationship with..said engine and positioned to successively pass closely adjacent to each of said stationary terminals, a television-radio suppression ignition cable extending between each said stationary terminal of said ignition distributor and the corresponding said resistor type spark plug, and an air gap between said ignition distributor movable terminal and each of said stationary terminals of a width within the range of .060 inch to .250 inch at the point of nearest approach.

2. An internal combustion engine radio frequency radiation suppressing ignition system comprising in combination, a resistor type spark plug of a resistance value within the range of 1,500 to 50,000 ohms for each cylinder of the internal combustion engine with which the ignition system is to be used, an

ignition distributor having a stationary terminal corresponding to each said resistor type spark plug and a movable terminal rotated in timed relationship with said engine and positioned to successively pass closely adjacent to each of said stationary terminals, a television-radio suppression ignition cable extending between each said stationary terminal of said ignition distributor and the corresponding said resistor-type spark plug,

and an air gap between said ignition distributor movable terminal and each of said stationary terminals of a width within the range of .060 inch to .250 inch at the point of nearest approach.

3. An internal combustion engine radio frequency radiation suppressing ignition system comprising in combination, a resistor type spark plug for each cylinder of the internal comto each said resistor type spark plug, a stationary center terminal and a movable terminal rotated in timed relationship with said engine and positioned to successively pass closely adjacent to each of said stationary terminals corresponding to said spark plugs and electrically connected to said stationary centerterminal, an ignition coil, a television-radio suppression ignition cable extending between each said stationary terminal of said ignition distributor corresponding to said spark plugs and the corresponding said resistor type spark plug and between said stationary center terminal and said ignition coil and an air gap between said ignition distributor movable terminal and each of said stationary terminals of a width within a range of .060 inch to .250 inch at the point ofinearest approach. I

4. An internal combustion engine radio frequency radiation ignition distributor having a stationary terminal corresponding 7 to each said resistor type spark plug, a stationary center terminal and a movable terminal rotated in timed relationship with said engine and positioned to successively pass closely adjacent to each of said stationary terminals, corresponding to said spark plugs and electrically connected to said stationary center terminal, an ignition coil, a televisionradio suppression ignition cable extending between each said stationary terminal of said ignition distributor corresponding to said spark plugs and the corresponding said resistor type spark plug and between said stationary center terminal and said ignition coil and an air gap between said ignition distributor movable terminal and each of said stationary terminals of a width within the range of .060 inch to .250 inch at a point of nearest approach.

5. A radio frequency radiation suppressing ignition system for an internal combustion engine having a plurality of spark plug receiving openings comprising in combination, anignition coil having a secondary winding and effective duringengine operation for producing a high potential pulse when each spark plug is to be energized, a distributor having arotating respective spark plug and having a resistance value of the order of 4,000 ohms per foot,-the length of each gap between said movable contact and each said stationary distributor contact when the same are in registration being an effectiveamount of the order of .090 inch for dampening the gap created discharge without substantially altering spark plug action 

